Substantial effort and attention continues toward the development of newer and more sustainable energy supplies. The conservation of energy by increased energy efficiency remains crucial to the world's energy future. According to an October 2010 report from the U.S. Department of Energy, heating and cooling account for 56% of the energy use in a typical U.S. home, making it the largest energy expense for most homes. Along with improvements in the physical plant associated with home heating and cooling (e.g., improved insulation, higher efficiency furnaces), substantial increases in energy efficiency can be achieved by better control and regulation of home heating and cooling equipment. By activating heating, ventilation, and air conditioning (HVAC) equipment for judiciously selected time intervals and carefully chosen operating levels, substantial energy can be saved while at the same time keeping the living space suitably comfortable for its occupants.
It would be beneficial, at both a societal level and on a per-home basis, for a large number of homes to have their existing older thermostats replaced by newer, microprocessor controlled “intelligent” thermostats having more advanced HVAC control capabilities that can save energy while also keeping the occupants comfortable. To do this, these thermostats will need more information from the occupants as well as the environments where the thermostats are located. Sensors in the home will gather real-time and historic data, such as occupancy data, to be used by thermostat to automate the HVAC controls. By analyzing this data, thermostats will make decisions on heating, cooling and saving energy. For at least this reason, it is important to make sure sensors used by thermostats produce accurate data. At the same time, however, there is a tension that can arise between increasing the number and kinds of sensors on the thermostat, on the one hand, while also provisioning the thermostat with a reasonably compact and visually pleasing form factor, on the other hand, for increasing the overall appeal of the intelligent thermostat to the purchasing public.